The drain mast comes out the bottom of the engine nacelle - right below the lower bifurcation. The drain mast actually is several different drains - one can determine what's leaking by which drain pipe the fluid is coming out of.
After engine start - especially if it's really cold (sub zero F), some of the seals don't seal well until they start to warm up. Small amounts of leakage (measured in "drips per minute") are allowed during this warmup period - but the leakage should stop when up to temperature.